If you want a workflow to check if another workflow is running you can test the the column that holds the workflow status. In the list view you will see something like: In progress, cancelled, etc. These status indicators can change depending on the language that SharePoint or Nintex is running in. So to make sure you don’t run in to language problems you can check the status based on the numerical value of the column.

2

In progress

3

Error occurred

4

Cancelled

5

Completed

6

Failed on Start (retrying)

These values can also be displayed by creating a view of the list that includes columns of each of the workflows and then viewing it in Edit Datasheet.

In some cases you are presented the wrong page when trying to approve a task that was created by a Nintex workflow. The one you see is the original SharePoint page. While instead you should see the one with the option “Approve” and “Reject”

The problem here seems to be a mismatch in the connection between the taskform and a contenttype.

There is solution to this problem. You need to set the right taskform to be shown with the NintexWorkflowTask content type.
Use the nwadmin command line tool with the SetTaskForm operation